As small-sized, large capacitance, and low ESR (Equivalent Series Resistance) capacitors, promising candidates are electrolytic capacitors including an anode body on which a dielectric layer is formed and a conductive polymer layer formed so as to cover at least a part of the dielectric layer.
In Unexamined Japanese Patent Publication No. 2012-174865, it is proposed, in a solid electrolytic capacitor that includes a capacitor element having a conductive polymer layer in the capacitor element, that, for example, a carbon layer be formed on a cathode foil of the capacitor element to suppress generation of an electrostatic capacity in a cathode. In Unexamined Japanese Patent Publication No. 2012-174865, the conductive polymer layer is formed through heat polymerization by immersing a wound body in a polymerization liquid containing a raw material of a conductive polymer, the wound body being obtained by winding an anode foil and the cathode with a separator interposed between the anode foil and the cathode.
In Unexamined Japanese Patent Publication No. 2008-010657, an electrolytic capacitor obtained by impregnating with an electrolyte solution a capacitor element is proposed. The electrolytic capacitor includes an anode foil on which a dielectric layer is formed, a cathode foil, a separator interposed between the anode foil and the cathode foil, and a conductive polymer layer formed on surfaces of the dielectric layer, the separator, and the cathode foil. In Unexamined Japanese Patent Publication No. 2008-010657, the conductive polymer layer is formed by impregnating the anode foil, the cathode foil, and the separator with a dispersion in which particles of a conductive polymer are dispersed.